Carbon support in arc lamp



April 22, 1958 H. scHERlNG ETAL CARBON SUPPORT IN ARC LAMP Filed July 7, 1955 INVENTOR. 4P/f United States Patent -O CARBON sUPPoRr 1N ARC LAMP `Helmuth Schering, Rudi Schmidt, and Kurt Flor, Dresden, Germany, assignorsA to VEB Zeiss Ikon, Dresden, Germany i' Application July 7, 1955, Serial No. 520,553

11 Claims. (Cl. S13- 35) High-capacity are lamps, especially those employed for background projection work, are generally equipped with rotating positive carbons to which current is supplied directly behind the burning end. The contact bushes for the supply of current, which are usually exchangeable to permit adaptation to different carbon diameters, are very much heated by the extraordinarily high crater temperatures and high amperages, so that the risk of charring of the points of contact and that of increased contact resistance must be eliminated. For this purpose cooling of the contact bushes is necessary, but the difficulty involved in this respect is that a closed cooling jacket preventing of course exchangeability of the bushes cannot be applied.

In order to overcome this difliculty the invention proposes to place the contact bushes between an approximately U-shaped supporting member through which a cooling agent flows and a supporting member disposed in the space between the sides of the U-shaped member and also traversed by a coolant. Owing to this arrangement, the contact bushes are almost completely surrounded by a coolant while still remaining exchangeable to permit adaptation to different carbon diameters.

One embodiment of the invention is illustrated in the accompanying drawing, in which:

Figure 1 is a section of the carbon support seen in the direction of the optical axis;

Fig. 2, a section on the line A--A of Fig. 1 seen vertically to the optical axis; and

Fig. 3 shows the collar of the contact bushes.

The rotating positive carbon 1 lies between the two contact bushes 2, 2. The upper bush 2 is taken up by the base portion of the stationary U-shaped supporting member 3 and the lower bush by the supporting member 4, a cooling agent flowing through passageways provided in both members 3 and 4. As can be seen, the bearing surfaces of the supporting members 3 and 4 are complementarily shaped relative to the outer surface of the bushes. The movable counter-supporting member 4 is guided in the space 6 formed by the sides 5, 5' of the U-shaped supporting member 3 and when the carbon is removed can be moved downwardly together with the two bushes against the action of the spring 7 by the handle 8 to facilitate their exchange. The spring 7 thus constitutes a resilient means urging the member 4 towards the base of the member 3. A guide pin 9 of the movable member 4 engages a recess 10 in the bush 2' to prevent movement of the contact bushes while the carbon is rotating. To preclude their displacement in the direction of the optical axis both bushes terminate in a collar 11 (Fig. 3) embracing the members 3 and 4. The collar 11 may be arranged, as shown, on both sides of the bushes or only on the side averted from the arc. To facilitate exchange of the bushes the collar may be reduced on two sides, as indicated in Fig. 3. l

Coolant is supplied to the movable member 4 and discharged therefrom through llexible tubes 12, 12' directly connected to the U-shaped member 3. A communication between the passageways of the members 3 and 4 is thus established. In this way the carbon support requires only two main pipings 13, 13' for connection with the coolant source.` The U-shaped supporting member 3 is secured to a base plate 14 of insulating material and thus insulated from the mass of the lamphouse.. Current is supplied to the U-shaped member 3 at 15.

We claim:

l. A carbon support for supporting a rotatable carbon of an arc lamp, comprising in combination: a first substantially U-shaped supporting member, a second supporting member movably arranged in the space defined by said U-shaped supporting member, a rst contact bush arranged in the space defined by said first and second supporting members,` said first contact bush being adapted to bear on the base of said first U-shaped supporting member and a carbon passing through the space defined by said first and second supporting members, a second contact bush arranged in the space defined by said first and second supporting members opposite said firstcontact bush, said second contact bush being adapted to bear on said second supporting member and said carbon, whereby said carbon is held between Said first and second contact bushes, and cooling means for cooling said first and second supporting members, said second supporting member being movable between a first position in which it urges said second contact bush into contact with said carbon whereby said carbon in turn is urged into contact with said first contact bush and a second position in which said second supporting member is situated farther away from the base of said first U-shaped supporting member, whereby said carbon and said contact bushes may be readily removed.

2. In a carbon support as claimed in claim l, said second supporting member being slidably arranged in the space defined by said first supporting member.

3. In a carbon support as claimed in claim 1, resilient means operatively engaged with said second supporting member for urging same towards the base of said first supporting member.

4. In a carbon support as claimed in claim 1, wherein the respective surfaces of said supporting members and said contact bushes which surfaces are adapted to bear on each other, are complementarily shaped.

5. ln a carbon support as claimed in claim l, wherein the surfaces of said first and second contact bushes adapted to bear on said carbon are each curved so as to define a semi-cylinder, whereby said surfaces in said first position form the defining walls of a hollow cylinder surrounding said carbon.

6. In a carbon support as claimed in claim 1, said first and second supporting members including passageways for conducting cooling liquid therethrough.

7. ln a carbon support as claimed in claim. 6, means for establishing communication between the passageways of said first and second supporting members.

8. In a carbon support as claimed in claim 1, said second contact bush having a recess and said second supporting member including a projecting pin member capable of engaging in said recess for preventing displacement of said second contact bush during rotation of said carbon.

9. In a carbon support as claimed in claim 1, said rst and second contact bushes terminating in collars capable of embracing said first and second supporting members respectively, for preventing displacement of said contact bushes in the longitudinal direction of said carbon.

10. A carbon support for supporting a rotatable carbon n of an arc lamp, comprising in combination'. a first substantially U-shaped supporting member, a second supporting member slidably arranged in the space defined by said rst supporting member, resilient means operatively engaged with said second supporting member for urging same towards the base of the U-shape-d supportingmernber, a rst contact bush arranged in the space defined by said rst and second supporting membersand including a curved inner bearing surface and an outer surface, said outer surface of said rst contact bush being adapted to bear on a complementarily shaped surface of said base, Said inner curved surface being adapted to bear on the cir cumference of a carbon passing through the space between said rst and second supporting members, a second contact bush arranged in the space defined by said rst and second supporting members opposite said rst Contact bush, said second Contact bush including an outer surface adapted to bear on a complementarily shaped surface of said second supporting member and an inner curved surface adapted to bear on the circumference of said carbon, said inner curved surfaces of said contact bushes each dening a semi-cylinder, and -said rst and second supporting members including passageways for conducting a cooling medium therethrough, said second supporting member being slidable between a rst position in which saidsecond. contact bush is urged into contact .with said carbon whereby said rst and second contact bushes form a hollow cylinder surrounding said carbon, and asecond position in which said second supporting member is farther removed from the base of said trst supporting member.

ll. Carbon support arranged at the burning end of `a rotating positive carbon of arc lamps, particularly highcapacity arcv lamps, comprising two current supplying and cooled contact bushes holding the rotating positive carbon between them and being exchangeable to permit adaptation to different carbon diameters, a stationary approximately U-shaped supporting member through which a cooling liquid passes, a movable supporting member disposed in the space formed between the sides of the stationary member and also provided with cooling liquid, said supporting members serving as holders for the contact bushes, and flexible tubes connected to the U-shaped member and supplying and discharging cooling liquid to and from said movable supporting member.

References Cited in the' tile of this patent UNITED STATES PATENTS 1,323,304 Mauclaire Dec.'2,r 1919 

